Container assemblies with releasable locking feature

ABSTRACT

A container assembly comprises first and second containers. The first container includes a first body portion and a first rim. The first rim has a first plurality of ribs projecting generally upwardly therefrom such that first spaces are formed between adjacent ribs. The first rim has a generally convex shape. The second container includes a second body portion and a second rim. The second rim has a second plurality of ribs projecting generally downwardly therefrom such that second spaces are formed between adjacent ribs. The second rim has a generally concave shape. The second container is shaped substantially the same as the first container. The first and second rims have shapes that correspond with each other when locked. The first and second containers are adapted to be releasably lockable by fitting the first plurality of ribs into respective second spaces and fitting the second plurality of ribs into respective first spaces.

RELATED APPLICATION

The present invention is a continuation-in-part application ofapplication Ser. No. 10/277,303 entitled “Containers and ContainerAssemblies with Releasable Locking Feature” that was filed on Oct. 22,2002, which is incorporated by reference in its entirety.

FIELD OF INVENTION

The present invention relates generally to container assemblies. Moreparticularly, the present invention relates to releasably lockablecontainer assemblies.

BACKGROUND OF THE INVENTION

The use of inexpensive polymeric, paper or metal packaging containershas become popular, especially for preparing and serving various foodproducts. Polymeric, paper and metal containers generally have been usedfor heating the food product(s) disposed therein. Container assembliestypically comprise a cover or lid and a base.

It would be desirable to have a container assembly that would be easyfor the customer to close and open. It would also be desirable toprovide a container assembly that is releasably lockable and prevents orinhibits material, such as liquid, from leaving the container.

SUMMARY OF THE INVENTION

According to one embodiment, a container assembly comprises a firstcontainer and a second container. The first container includes a firstcontinuous body portion and a first rim. The first rim encompasses andprojects laterally outwardly from the first body portion. The first rimhas a first plurality of ribs projecting generally upwardly therefromsuch that first spaces are formed between adjacent ribs. The first rimhas a generally convex shape. The second container includes a secondcontinuous body portion and a second rim. The second rim encompasses andprojects laterally outwardly from the second body portion. The secondrim has a second plurality of ribs projecting generally downwardlytherefrom such that second spaces are formed between adjacent ribs. Thesecond rim has a generally concave shape. The second container is shapedsubstantially the same as the first container. The first rim and thesecond rim have shapes that correspond with each other when beingreleasably lockable to each other. The first container and the secondcontainer are adapted to be releasably lockable to each other by fittingthe first plurality of upwardly-projecting ribs into respective secondspaces and fitting the second plurality of downwardly-projecting ribsinto respective first spaces.

According to one method, a container assembly is formed by providing afirst container that includes a first continuous body portion and afirst rim. The first rim encompasses and projects laterally outwardlyfrom the first body portion. The first rim has a first plurality of ribsprojecting generally upwardly therefrom such that first spaces areformed between adjacent ribs. The first rim has a generally convexshape. A second container is provided that includes a second continuousbody portion and a second rim. The second rim encompasses and projectslaterally outwardly from the second body portion. The rim has a secondplurality of ribs projecting generally downwardly therefrom such thatsecond spaces are formed between adjacent ribs. The second rim has agenerally concave shape. The second container is shaped substantiallythe same as the first container. One of the first container and thesecond container is flipped such that the first container and secondcontainer are generally aligned, the first and second rims are next toeach other, and the first and second rims correspond with each othersuch that the first and second rims are either both in a generallyconcave orientation or a generally convex orientation. The firstplurality of upwardly-projecting ribs fits into respective second spacesand the second plurality of downwardly-projecting ribs fits intorespective first spaces such that the first container and the secondcontainer are releasably lockable to each other.

According to another embodiment, a container assembly comprises a firstcontainer and a second container. The first container includes a firstcontinuous body portion and a first rim. The first rim encompasses andprojects laterally outwardly from the first body portion. The first rimhas a first plurality of upwardly projecting features with first spacesbeing formed between adjacent upwardly projecting features. The firstrim has a generally convex shape. The second container includes a secondcontinuous body portion and a second rim. The second rim encompasses andprojects laterally outwardly from the second body portion. The rim has asecond plurality of downwardly projecting features with second spacesbeing formed between adjacent downwardly projecting features. The secondrim has a generally concave shape. The second container is shapedsubstantially the same as the first container. The first container andthe second container are adapted to be releasably lockable to each otherby fitting the first plurality of upwardly projecting features intorespective second spaces and fitting the second plurality of downwardlyprojecting features into respective first spaces.

According to a further embodiment, a container assembly comprises afirst container and a second container. The first container includes afirst continuous body portion and a first rim. The first rim encompassesand projects laterally outwardly from the first body portion. The firstrim has a generally convex shape. The first rim has a first plurality ofribs projecting generally upwardly therefrom such that first spaces areformed between adjacent ribs. The first plurality of upwardly-projectingribs creates a first pattern that is generally normal to the directionof the first rim. The first plurality of upwardly-projecting ribs has atleast one undercut. The second container includes a second continuousbody portion and a second rim. The second rim encompasses and projectslaterally outwardly from the second body portion. The second rim has agenerally concave shape. The second rim has a second plurality of ribsprojecting generally downwardly therefrom such that second spaces areformed between adjacent ribs. The second plurality ofdownwardly-projecting ribs creates a second pattern that is generallynormal to the direction of the second rim. The second plurality ofdownwardly-projecting ribs has at least one undercut. The secondcontainer is shaped substantially the same as the first container. Thefirst container and the second container are adapted to be releasablylockable to each other by fitting the first plurality ofupwardly-projecting ribs into respective second spaces and fitting thesecond plurality of downwardly-projecting ribs into respective firstspaces.

According to yet another embodiment, a container assembly comprises afirst container and a second container. The first container includes afirst continuous body portion and a first rim. The first rim encompassesand projects laterally outwardly from the first body portion. The firstrim has a first plurality of ribs projecting generally upwardlytherefrom such that first spaces are formed between adjacent ribs. Thefirst rim has a generally convex shape. The second container includes asecond continuous body portion and a second rim. The second rimencompasses and projects laterally outwardly from the second bodyportion. The second rim has a second plurality of ribs projectinggenerally downwardly therefrom such that second spaces are formedbetween adjacent ribs. The second rim has a generally concave shape. Thefirst rim and the second rim have shapes that correspond with each otherwhen being releasably lockable to each other. The first container andthe second container are adapted to be releasably lockable to each otherby fitting the first plurality of upwardly-projecting ribs intorespective second spaces and fitting the second plurality ofdownwardly-projecting ribs into respective first spaces.

According to another method, a container assembly is formed by providinga first container that includes a first continuous body portion and afirst rim. The first rim encompasses and projects laterally outwardlyfrom the first body portion. The first rim has a first plurality of ribsprojecting generally upwardly therefrom such that first spaces areformed between adjacent ribs. The first rim has a generally convexshape. A second container is provided that includes a second continuousbody portion and a second rim. The second rim encompasses and projectslaterally outwardly from the second body portion. The rim has a secondplurality of ribs projecting generally downwardly therefrom such thatsecond spaces are formed between adjacent ribs. The second rim has agenerally concave shape. One of the first container and the secondcontainer is flipped such that the first container and second containerare generally aligned, the first and second rims are next to each other,and the first and second rims correspond with each other such that thefirst and second rims are either both in a generally concave orientationor a generally convex orientation. The first plurality ofupwardly-projecting ribs fits into respective second spaces and thesecond plurality of downwardly-projecting ribs fits into respectivefirst spaces such that the first container and the second container arereleasably lockable to each other.

According to yet a further embodiment, a container assembly comprises afirst container and a second container. The first container includes afirst continuous body portion and a first rim. The first rim encompassesand projects laterally outwardly from the first body portion. The firstrim has a first plurality of upwardly projecting features with firstspaces being formed between adjacent upwardly projecting features. Thefirst rim has a generally convex shape. The second container includes asecond continuous body portion and a second rim. The second rimencompasses and projects laterally outwardly from the second bodyportion. The rim has a second plurality of downwardly projectingfeatures with second spaces being formed between adjacent downwardlyprojecting features. The second rim has a generally concave shape. Thefirst container and the second container are adapted to be releasablylockable to each other by fitting the first plurality of upwardlyprojecting features into respective second spaces and fitting the secondplurality of downwardly projecting features into respective firstspaces.

According to another embodiment, a container assembly comprises a firstcontainer and a second container. The first container includes a firstcontinuous body portion and a first rim. The first rim encompasses andprojects laterally outwardly from the first body portion. The first rimhas a generally convex shape. The first rim has a first plurality ofribs projecting generally upwardly therefrom such that first spaces areformed between adjacent ribs. The first plurality of upwardly-projectingribs creates a first pattern that is generally normal to the directionof the first rim. The first plurality of upwardly-projecting ribs has atleast one undercut. The second container includes a second continuousbody portion and a second rim. The second rim encompasses and projectslaterally outwardly from the second body portion. The second rim has agenerally concave shape. The second rim has a second plurality of ribsprojecting generally downwardly therefrom such that second spaces areformed between adjacent ribs. The second plurality ofdownwardly-projecting ribs creates a second pattern that is generallynormal to the direction of the second rim. The second plurality ofdownwardly-projecting ribs has at least one undercut. The firstcontainer and the second container are adapted to be releasably lockableto each other by fitting the first plurality of upwardly-projecting ribsinto respective second spaces and fitting the second plurality ofdownwardly-projecting ribs into respective first spaces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a side view of a first container to be used in oneembodiment of the invention.

FIG. 1 b is a top view of the first container of FIG. 1 a.

FIG. 1 c is an enlarged top perspective view of a portion of the firstcontainer of FIG. 1 a.

FIG. 1 d is an enlarged view of area labeled FIG. 1 d in FIG. 1 c;

FIG. 1 e is an outline of the periphery of the first container of FIG. 1a.

FIG. 2 a is a side view of a second container to be used in oneembodiment of the invention.

FIG. 2 b is a top view of the second container of FIG. 2 a.

FIG. 2 c is an enlarged top perspective view of a portion of the secondcontainer of FIG. 2 a.

FIG. 2 d is an enlarged view of area labeled FIG. 2 d in FIG. 2 c;

FIG. 2 e is an outline of the periphery of the second container of FIG.2 a.

FIG. 3 a is a side view of a container assembly using the firstcontainer of FIG. 1 a and the second container of FIG. 2 a.

FIG. 3 b is an outline of the peripheries of the first and secondcontainers used to form the container assembly of FIG. 3 a.

FIG. 3 c is an enlarged cross-sectional view depicting the engagementbetween the ribs of the first and second containers;

FIG. 4 is an outline of the periphery of the first container accordingto another embodiment.

FIG. 5 a is a side view of a first container to be used in anotherembodiment of the invention.

FIG. 5 b is a top view of the first container of FIG. 5 a.

FIG. 5 c is a top view of the generally circular region FIG. 5 c of FIG.5 a depicting two adjacent projecting ribs.

FIG. 5 d is a perspective view of the generally circular region FIG. 5 cof FIG. 5 a depicting two adjacent projecting ribs.

FIG. 6 a is a side view of a second container to be used in anotherembodiment of the invention.

FIG. 6 b is a top view of the second container of FIG. 6 a.

FIG. 7 a is a side view of a container assembly using the firstcontainer of FIG. 5 a and the second container of FIG. 6 a.

FIG. 7 b is an outline of the peripheries of the first and secondcontainers used to form the container assembly of FIG. 7 a.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawing and will herein be described in detail. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed but, on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theappended claims.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to FIGS. 1 a-e, 2 a-e, a first container (e.g., plate 10) anda second container (e.g., plate 110) to be used in one embodiment of thepresent invention are shown. The plate 10 of FIGS. 1 a-e is used with asecond plate 110 of FIGS. 2 a-e that may be substantially the same tothe plate 10 to form a container assembly that is releasably lockable.

It is contemplated that other container assemblies may be formed besidesthose using plates. For example, container assemblies may be formed, butare not limited to, using plates, bowls, platters, tubs, single-serveand family-size containers, single-serve and family-size ovenware, andcombinations thereof. One such combination is a bowl and a plate thatforms a container assembly. The remainder of the application willdiscuss container assemblies with respect to plates although it isrecognized by one of ordinary skill in the art that other containerassemblies, such as those discussed above, may be formed.

The height and shape of the container assembly may vary from that shownwithout departing from the scope of the invention. For example, thecontainer assembly of FIGS. 3 a, 3 b as will be discussed, are depictedas being generally circular. It is contemplated that the containerassemblies and containers for forming the container assemblies usedherein may be other shapes such as rectangular, square, hexagonal,octagonal, other polygonal shapes, or oval.

The container assemblies of the present invention are typically usedwith respect to food, but may be used in other applications such as withmedical applications, cosmetics or other items. Food containerassemblies may be used for serving, storing, preparing and/or re-heatingthe food.

Referring back to FIGS. 1 a-e, the container 10 includes a continuousbody portion 12 and a continuous rim 14 encompassing and projectinglaterally outwardly from the body portion 12. As shown in FIGS. 1 a, 1e, the rim 14 has a generally convex shape. Referring back to FIGS. 1a-1 e, the body portion 12 includes a bottom 16 and a continuoussidewall 18 encompassing and projecting upwardly and outwardly from thebottom 16. It is contemplated that the sidewall may project onlyupwardly from the bottom 16 or even project upwardly and inwardly fromthe bottom 16. It is also contemplated that the rim may not becontinuous, although it is preferred to be continuous.

Referring specifically to FIGS. 1 a-d, the continuous rim 14 includes aplurality of ribs 20 that project generally upwardly therefrom. Theplurality of ribs 20 is spaced around the general periphery of thecontainer 10 and assists in forming a releasably lockable containerassembly. The orientation of the plurality of ribs 20 creates a patternthat is generally normal to the direction of the rim 14. Morespecifically, the orientation of the plurality of ribs 20 may create apattern that is normal to the direction of the rim 14. In a radialconfiguration with a pattern that is normal to the direction of the rim,each of the plurality of ribs 20, if extended inwardly, would passthrough the general center of the plate.

The plurality of ribs 20, however, may be formed in different patternsthan shown in FIGS. 1 a-d with respect to the rim 14 (e.g., diagonally).It may be desirable to form the plurality of ribs 20 in a decorativepattern for aesthetic reasons. Such a decorative feature may assist in“hiding” or disguising the releasable lockable feature in the container10. As shown in FIG. 1 b, the container 10 has exactly 48 ribs formed inthe continuous rim 14. It is contemplated that the number of ribs mayvary from that shown in FIG. 1 b. For example, a container may have fromabout 3 to about 10 ribs. A container may have greater than about 20 orabout 40 ribs, and may even have up to or greater than about 120 ribs.The desired number of ribs formed on the container will often varydepending on factors such as the size or shape of the containerassembly, the material(s) type and thicknesses of the containerassembly, and the desired holding strength of the container assembly.The desired holding strength depends on factors such as the weight ofitem(s) placed in the container assembly and its perceived usage.

Turning specifically to FIGS. 1 c, 1 d, the plurality of ribs 20 isshown in greater detail. FIGS. 1 c, 1 d depict a first rib 20 a and asecond rib 20 b with a space 22 being formed therebetween. The first rib20 a of FIG. 1 d comprises a generally flat surface 24 that bridges twosidewalls 26, 28. The first rib 20 a is shown as being generallyperpendicular to the plane of the remainder of the continuous rim 14.More specifically, the rib may be perpendicular to the plane of theremainder of the rim. The sidewalls 26, 28 are spaced apart from eachother and are shown as being generally perpendicular to the plane of theremainder of the rim 14. The sidewalls 26, 28, however, do notnecessarily have to be generally perpendicular or perpendicular to theremainder of the rim 14.

Similarly, second rib 20 b of FIG. 1 d comprises a generally flatsurface 30 that bridges two sidewalls 32, 34. The second rib 20 b isalso shown as being generally perpendicular to the plane of theremainder of the rim 14. The sidewalls 32, 34 are spaced apart from eachother and are shown as being generally perpendicular to the plane of theremainder of the rim 14.

To provide an improved locked container assembly, at least one of therib sidewalls may have an undercut. Such an optional undercut formed inthe rib sidewall engages a similar undercut in a corresponding spaceformed between adjacent ribs of a second container when the containerassembly is formed. For example, in FIG. 1 d, optional undercuts 26 a,28 a are formed in respective sidewalls 26, 28. The size and shape ofthe undercut will often vary depending on factors such as the size orshape of the container assembly, the material(s) type and thicknesses ofthe container assembly, and the desired holding strength of thecontainer assembly. The desired holding strength may depend on factorssuch as the weight of item(s) placed in the container assembly and itsperceived usage.

The number of undercuts formed in the rib sidewalls, if any, depends onfactors such as the desired leak-resistant, the type of closuremechanism, manufacturability of the container assemblies, and thematerial(s) type and thicknesses used in forming the containerassemblies. For example, if the container assemblies are made of a firstmaterial that has a higher coefficient of friction than a secondmaterial, then the container made of the first material will likely needless undercuts in its sidewalls than the same container made with thesecond material to have the same holding strength. The number ofundercuts used also depends on the fitness of use of the containerassembly, including the holding strength thereof.

It is contemplated that the ribs may have sidewalls with no undercuts orat least one undercut (e.g., first rib 20 a with optional undercuts 26a, 28 a in FIG. 1 d). It is also contemplated that some ribs within thesame container may have no undercuts, while other ribs may have one ormore undercuts.

It is contemplated that the shape and size of the plurality of ribs 20may vary from that shown in FIGS. 1 c, 1 d. It is preferred that theplurality of ribs be shaped and sized to minimize the stacking height ofthe containers used to form container assemblies. It is desirable tominimize the stacking height of the containers to (a) reducetransportation costs and packaging, and (b) provide space efficiency inretail and consumer settings. It is also desirable to maximize theholding strength of the container assembly. The desired holding strengthis often a balance between making the container assembly easy for aconsumer to open and close, while still preventing or inhibiting aninadvertent opening of the container assembly.

It is contemplated that the upwardly-projecting features may be shapeddifferently than the ribs shown in FIGS. 1 c, 1 d. For example, theupwardly-projecting features may be a plurality of round, oval, square,or polygonal features. It is contemplated that many shapes and sizes maybe formed by the upwardly-projecting features used in the firstcontainer.

Referring to FIG. 4, a first container 50 includes a rim 52 in which therim forms an optional seal feature 54 and a rib 56. The rim 52 is shownas being generally convex. In FIG. 4, the optional seal feature 54 islocated outwardly from the rib 56 with respect to the center of thecontainer 50. In other words, the optional seal feature 54 is locatedfarther away from the center of the container 50 than the rib 56. Theoptional seal feature 54 in conjunction with a corresponding optionalseal feature on a second container with a generally concave rim (notshown), along with the locked ribs of the container assembly, assist inpreventing or inhibiting material from leaving or entering the containerassembly. The optional seal feature is especially useful in preventingor inhibiting product leakage that may occur due to tolerances withinthe manufacturing process. To provide an efficient seal, the height H1of the optional seal feature 54 should be at least one-half of the ribheight H2.

The optional seal feature, however, may be located inwardly from theribs such that the seal is formed nearer the center of the containerassembly as compared to the releasably lockable ribs.

Referring back to FIGS. 2 a-e, the container 110 includes a continuousbody portion 112 and a continuous rim 114 encompassing and projectinglaterally outwardly from the body portion 112. As shown in FIG. 2 b, therim 114 has a generally concave shape. The body portion 112 includes abottom 116 and a continuous sidewall 118 encompassing and projectingupwardly and outwardly from the bottom 116. It is contemplated that thesidewall may project only upwardly from the bottom 116 or even projectupwardly and inwardly from the bottom 116. It is also contemplated thatthe rim may not be continuous, although it is preferred to becontinuous.

Referring specifically to FIGS. 2 a-d, the continuous rim 114 includes aplurality of ribs 120 that project generally downwardly therefrom. Theplurality of ribs 120 is spaced around the general periphery of thecontainer 110 and assists in forming a releasably lockable containerassembly. The orientation of the plurality of ribs 120 creates a patternthat is generally normal to the direction of the rim 114. Morespecifically, the orientation of the plurality of ribs 120 may create apattern that is normal to the direction of the rim 114. In a radialconfiguration with a pattern that is normal to the direction of the rim,each of the plurality of ribs 120, if extended inwardly, would passthrough the general center of the plate.

The plurality of ribs 120, however, may be formed in different patternsthan shown in FIGS. 2 a-d with respect to the rim 114 (e.g.,diagonally). It may be desirable to form the plurality of ribs 120 in adecorative pattern for aesthetic reasons. Such a decorative feature mayassist in “hiding” or disguising the releasable lockable feature in thecontainer 110. As shown in FIG. 2 b, the container 110 has exactly 48ribs formed in the continuous rim 114. It is contemplated that thenumber of ribs may vary from that shown in FIG. 2 b. For example, acontainer may have from about 3 to about 10 ribs. A container may havegreater than about 20 or about 40 ribs, and may even have up to orgreater than about 120 ribs. The desired number of ribs formed on thecontainer will often vary depending on factors such as the size or shapeof the container assembly, the material(s) type and thicknesses of thecontainer assembly, and the desired holding strength of the containerassembly. The desired holding strength depends on factors such as theweight of item(s) placed in the container assembly and its perceivedusage.

Turning specifically to FIGS. 2 c, 2 d, the plurality of ribs 120 isshown in greater detail. FIGS. 2 c. 2 d depict a first rib 120 a and asecond rib 120 b with a space 122 being formed therebetween. The firstrib 120 a of FIG. 1 d comprises a generally flat surface 124 thatbridges two sidewalls 126, 128. The first rib 120 a is shown as beinggenerally perpendicular to the plane of the remainder of the continuousrim 114. More specifically, the rib may be perpendicular to the plane ofthe remainder of the rim. The sidewalls 126, 128 are spaced apart fromeach other and are shown as being generally perpendicular to the planeof the remainder of the rim 114. The sidewalls 126, 128, however, do notnecessarily have to be generally perpendicular or perpendicular to theremainder of the rim 14.

Similarly, second rib 120 b of FIG. 2 d comprises a generally flatsurface 130 that bridges two sidewalls 132, 134. The second rib 120 b isalso shown as being generally perpendicular to the plane of theremainder of the rim 114. The sidewalls 132, 134 are spaced apart fromeach other and are shown as being generally perpendicular to the planeof the remainder of the rim 114.

To provide an improved locked container assembly, at least one of therib sidewalls may have an undercut. Such an optional undercut formed inthe rib sidewall engages a similar undercut in a corresponding spaceformed between adjacent ribs of a second container when the containerassembly is formed. For example, in FIG. 2 d, optional undercuts 126 a,128 a are formed in respective sidewalls 126, 128. The size and shape ofthe undercut will often vary depending on factors such as the size orshape of the container assembly, the material(s) type and thicknesses ofthe container assembly, and the desired holding strength of thecontainer assembly. The desired holding strength may depend on factorssuch as the weight of item(s) placed in the container assembly and itsperceived usage.

The number of undercuts formed in the rib sidewalls, if any, depends onfactors such as the desired leak-resistant, the type of closuremechanism, manufacturability of the container assemblies, and thematerial(s) type and thicknesses used in forming the containerassemblies. For example, if the container assemblies are made of a firstmaterial that has a higher coefficient of friction than a secondmaterial, then the container made of the first material will likely needless undercuts in its sidewalls than the same container made with thesecond material to have the same holding strength. The number ofundercuts used also depends on the fitness of use of the containerassembly, including the holding strength thereof.

It is contemplated that the ribs may have sidewalls with no undercuts orat least one undercut (e.g., first rib 120 a with optional undercuts 126a, 128 a in FIG. 2 c). It is also contemplated that some ribs within thesame container may have no undercuts, while other ribs may have one ormore undercuts.

It is contemplated that the shape and size of the plurality of ribs 120may vary from that shown in FIGS. 2 c, 2 d. It is preferred that theplurality of ribs be shaped and sized to minimize the stacking height ofthe containers used to form container assemblies. It is desirable tominimize the stacking height of the containers to (a) reducetransportation costs and packaging, and (b) provide space efficiency inretail and consumer settings. It is also desirable to maximize theholding strength of the container assembly. The desired holding strengthis often a balance between making the container assembly easy for aconsumer to open and close, while still preventing or inhibiting aninadvertent opening of the container assembly.

It is contemplated that the downwardly projecting features may be shapeddifferently than the ribs shown in FIGS. 2 c, 2 d. For example, thedownwardly projecting features may be a plurality of round, oval,square, or polygonal features. It is contemplated that many shapes andsizes may be formed by the downwardly projecting features used in thesecond container.

A container assembly 100 according to one embodiment of the presentinvention is depicted in FIGS. 3 a, 3 b. The container assembly 100comprises the first container 10 and the second container 110.

According to one method, the second container 110 is flipped 180 degreesrelative to the first container 10 such that the containers 10, 110 aregenerally aligned and the rims 14, 114 are adjacent to each other. Thisflipped position of container 110 relative to the container 10 is shownin FIG. 3 a. To fit the ribs into respective spaces, the container 110may have to be rotated slightly such that the ribs are offset (i.e., theribs and spaces are aligned). It is desirable that the consumer canassembly the containers so as to form a container assembly of thepresent invention.

Referring to FIG. 3 c, adjacent ribs 120 a, 120 b of the container 110are fit into respective second spaces 22 a, 22 b of the container 10 andribs 20 a, 20 b of the container 10 are fit into respective spaces 122a, 122 b such that the container assembly 100 is releasably lockable. Tofit the ribs into respective spaces, the container 110 may have to berotated slightly such that the ribs are offset (i.e., the ribs andspaces are aligned). FIG. 3 c also depicts interference areas 124 a, 124b formed between the first rib 20 a and the space 122 a created betweenribs 120 a, 120 b of the container 110.

The strength of this lockable closure is dependent on many variablessuch as the number of the projecting ribs, the height of those ribs,whether undercuts are included, the size of the contact areas, theclearance needed between spaces and ribs, and the material(s) type andthickness used in forming the container assemblies. To improve thelockability of the container assembly, as discussed above, an optionalsealing feature may be added.

Referring to FIGS. 5 a, 5 b, a first container (e.g., plate 210)includes a continuous body portion 212 and a continuous rim 214encompassing and projecting laterally outwardly from the body portion212. As shown in FIG. 5 a, the rim 214 has a generally convex shape. Thebody portion 212 includes a bottom 216 and a continuous sidewall 218encompassing and projecting upwardly and outwardly from the bottom 216.It is contemplated that the sidewall may project only upwardly from thebottom 216 or even project upwardly and inwardly from the bottom 216. Itis also contemplated that the rim may not be continuous, although it ispreferred to be continuous.

Referring to FIGS. 5 a-5 d, the continuous rim 214 includes a pluralityof rib sets 220 that project generally upwardly therefrom. The pluralityof rib sets 220 is spaced around the general periphery of the container210 and assists in forming a releasably lockable container assembly. Theorientation of the plurality of rib sets 220 creates a pattern that isgenerally parallel or generally concentric with the general direction ofthe rim 214. In other words, each of the plurality of rib sets 220, ifextended outwardly, would be no closer to the general center of thecontainer 210. The plurality of rib sets 220 is in the oppositedirection of the plurality of ribs 20 in FIGS. 1-3.

The plurality of rib sets 220, however, may be formed in differentpatterns than shown in FIG. 5 b with respect to the rim 214 (e.g.,diagonally). It may be desirable to form the plurality of rib sets 220in a decorative pattern for aesthetic reasons. Such a decorative featuremay assist in “hiding” or disguising the releasable lockable feature inthe container 210.

The container 210 of FIG. 5 b has exactly 30 sets of ribs formed in thecontinuous rim 214. As will be discussed in more detail below, each ofthe plurality of rib sets 220 has a first set of ribs on a raisedportion and a second set of ribs on a recessed portion. It iscontemplated that the number of rib sets may vary from that shown inFIG. 5 b. For example, a container may have from about 2 to about 30sets of ribs. A container may have greater than about 40 or about 80sets of ribs, and may even have up to or greater than about 120 sets ofribs. The desired number of ribs formed on the container will often varydepending on factors such as the size or shape of the containerassembly, the material(s) type and thicknesses of the containerassembly, and the desired holding strength of the container assembly.The desired holding strength may depend on factors such as the weight ofitem(s) placed in the container assembly and its perceived usage.

Turning to FIGS. 5 c, 5 d, two adjacent sets of ribs are shown ingreater detail. The number of ribs in a set varies in FIGS. 5 c, 5 ddepending on whether the ribs are located in a recessed area or a raisedarea formed in the rim 214. For example, in FIGS. 5 c, 5 d, recessedarea 240 has a first rib 242 and a second rib 244 with spaces 246, 248and 250. Raised area 260 of FIGS. 5 c, 5 d, however, has a first rib262, a second rib 264, and a third rib 266 with spaces 268, 270therebetween.

Each of the ribs of FIG. 5 c projects upwardly from the continuous rim214. For example, the first rib 242 of FIG. 13 comprises a generallyflat surface 242 a that bridges two sidewalls 242 b, 242 c. The firstrib 242 is shown as being generally perpendicular to the plane of theremainder of the continuous rim 214. The sidewalls 242 b, 242 c arespaced apart from each other and are shown as being generallyperpendicular to the plane of the remainder of the rim 214. Thesidewalls 242 b, 242 c, however, do not necessarily have to be generallyperpendicular or perpendicular to the remainder of the rim 214.

To provide an improved locked container assembly, at least one of therib sidewalls may have an optional undercut. As discussed above, such anundercut formed in the rib sidewall engages a similar undercut in thespaces formed between adjacent ribs when the container assembly isformed. The size and shape of the undercut will often vary depending onfactors such as the size or shape of the container assembly, thematerial(s) type and thicknesses of the container assembly, and thedesired holding strength of the container assembly. The desired holdingstrength may depend on factors such as the weight of item(s) placed inthe container assembly and its perceived usage.

As discussed above, the number of undercuts formed in the rib sidewalls,if any, depends on several factors. It is contemplated that the ribs mayhave sidewalls with no undercuts or at least one undercut. It is alsocontemplated that some ribs within the same container may have noundercuts, while other ribs have one or more undercuts.

The raised and recessed areas 240, 260 of FIG. 5 d have a plurality ofribs with generally flat areas. For example, the rib 242 includes thetop surface or generally flat area 242 a. Similarly, the rib 264includes a top surface or generally flat area 264 a. To improve thesealability of the container assembly, the generally flat areas 264 a,242 a may contact similar sized flat areas formed in the spaces formedbetween adjacent ribs of a second container that forms the containerassembly. An example of a similar sized flat area formed in a space isdepicted in FIG. 5 d with space 246. As shown in FIG. 5 d, a generallyflat area 282 is formed between adjacent sets of ribs (i.e., the raisedand recessed portions) to assist in releasably locking the containerassembly. It is contemplated that this area of the ribs may be sized andshaped differently than shown in FIGS. 5 c, 5 d. It is contemplated thatthe numbers of ribs in a set of ribs may vary from that shown in FIGS. 5c, 5 d (two ribs in the recessed areas and three ribs in the raisedareas).

It is contemplated that the first container 210 may include shape andsize of the plurality of ribs 220 may vary from that shown in FIGS. 5b-d. It is preferred that the plurality of ribs be shaped and sized tominimize the stacking height of the containers. It is desirable tominimize the stacking height of the containers to (a) reducetransportation costs and packaging, and (b) provide space efficiency inretail and consumer settings. It is also desirable to maximize theholding strength of the container assembly. The desired holding strengthis often a balance between making the container assembly easy for aconsumer to open and close, while still preventing or inhibiting aninadvertent opening of the container assembly.

It is contemplated that the first container 210 may include an optionalseal feature formed on the rim 214. The optional seal feature may belocated outwardly from the ribs 242, 244, 262, 264 and 266 of FIGS. 5 c,5 d with respect to the center of the container 210. In other words, theoptional seal feature may be located farther away from the center of thecontainer 210 than the ribs. The optional seal feature in conjunctionwith a corresponding seal feature on another container, along with thelocked ribs of the container assembly, assist in preventing orinhibiting material from leaving or entering the container assembly. Theoptional seal feature is especially useful in preventing or inhibitingproduct leakage that may occur due to tolerances within themanufacturing process. Such an optional seal feature may be formedsimilarly to the optional seal feature 54 in FIG. 4.

The optional seal feature, however, may be located inwardly from theribs such that the seal is formed nearer the center of the containerassembly as compared to the releasably lockable ribs.

Turning to FIGS. 6 a, 6 b, the second container 310 includes acontinuous body portion 312 and a continuous rim 314 that encompassesand projects laterally outwardly from the body portion 312. Thecontinuous rim 314 has a generally concave shape. The body portion 312includes a bottom 316 and a continuous sidewall 318 encompassing andprojecting upwardly and outwardly from the bottom 316. It iscontemplated that the sidewall may project only upwardly from the bottom316 or even project upwardly and inwardly from the bottom 216. It isalso contemplated that the rim may not be continuous, although it ispreferred to be continuous. The second container 310 is the same as thefirst container 210 except that the continuous rim 214 of the firstcontainer has a generally convex shape, while the continuous rim 314 ofthe second container has a generally concave shape.

A container assembly 400 according to one embodiment of the presentinvention is depicted in FIGS. 7 a, 7 b. The container 400 comprises thefirst container 210 of FIGS. 5 a-d and the second container 310 of FIGS.6 a, 6 b. In one embodiment, the second container 310 is shapedsubstantially the same as the first container 210. As discussed above,the container assembly may be formed with different first and secondcontainers than plates. For example, the container assembly may beformed using a bowl and a plate.

The container assembly 400 of FIGS. 7 a, 7 b may be formed according toone method by providing the first container 210 and the second container310. As discussed above with container assembly 100, the secondcontainer 310 is flipped 180 degrees relative to the first container 210such that the containers 210, 310 are generally aligned and the rims214, 314 are adjacent to each other. This flipped position of thecontainer 310 relative to the container 210 is shown in FIGS. 7 a, 7 b.

The container assemblies of the present invention are typically formedfrom polymeric materials, but may be formed from materials such as paperor metal. The polymeric container assemblies may be formed frompolyolefins. The polymeric food container assemblies are typicallyformed from orientated polystyrene (OPS), polyethylene terephthalate(PET), polyvinyl chloride (PVC), polypropylene and combinations thereof.The containers assemblies may be made from a mineral-filled polymericmaterial such as, for example, talc or calcium carbonate-filledpolyolefin. An example of paper that may be used in forming thecontainer assemblies is paperboard or molded fiber. Paperboard andmolded fiber typically have a sufficient coefficient of friction tomaintain the first and second containers in a lockable position.

As discussed, the materials used in forming the container assembly mayassist in releasably locking the container assembly. For example, thematerial(s) forming the container assembly may have a fairly tackylaminate on one side that corresponds with a fairly tacky laminate onthe opposing side, resulting in a desirable releasably lockablecontainer assembly.

It is contemplated that the containers used in forming the containerassemblies may be made from different materials. It is contemplated thatone of ordinary skill in the art will recognize that other polymers orcombination of polymers may be used to form the containers.

The container assemblies of the present invention are typicallydisposable, but it is contemplated that they may be reused at a futuretime. The containers used in forming the container assemblies (e.g.,containers 10, 110) are shown as including one compartment. It iscontemplated that the containers may be formed of multiple compartments.Such containers are desirable for placing items (e.g., food items) indifferent compartments to prevent or inhibit commingling of items. Forexample, undesirable mixing of food items can corrupt the flavor and theconsistency of the food items.

As discussed above, the container assemblies may be used with fooditems. A method of using such container assemblies includes placing thefood and locking the containers to form a container assembly with foodtherein. The container assembly is then placed in a heating apparatusand heated. Typical heating apparatuses include microwaves andconventional ovens. The container assemblies may contain solid foodproducts. The container assemblies may be used for storage in therefrigerator and/or the freezer.

The containers to be used in forming the container assemblies of thepresent invention may be formed using conventional thermoforming (e.g.,by pressure, vacuum or the combination thereof), injection-moldingprocesses, or rotational molding. According to one method ofthermoforming, pellets of a polymeric resin and additives, if any, areadded into an extruder. The pellets of the polymeric resin andadditives, if any, are melted to form a blend. The blend is extrudedthrough a die to form an extruded sheet. The extruded sheet isthermoformed to a desired shape of a container to be used in forming thecontainer assembly.

The thickness of the container to be used in forming the containerassemblies generally ranges from about 0.002 to about 0.15 inch, but istypically from about 0.005 to about 0.04 inch. The container assembliesmay be opaque or a variety of colors or color combinations. Thecontainer assemblies typically have at least one transparent containerif it is desired for the customer to ascertain the nature of theaccommodated product and the condition thereof without having to openthe container assembly.

While particular embodiments and applications of the present inventionhave been illustrated and described, it is to be understood that theinvention is not limited to the precise construction and compositionsdisclosed herein and that various modifications, changes, and variationsmay be apparent from the foregoing descriptions without departing fromthe spirit and scope of the invention as defined in the appended claims.

1. A container assembly comprising: a first container including a firstcontinuous body portion and a first rim, the first rim encompassing andprojecting laterally outwardly from the first body portion, the firstrim having a first plurality of ribs projecting generally upwardlytherefrom such that first spaces are formed between adjacent ribs, thefirst rim having a generally convex shape; and a second containerincluding a second continuous body portion and a second rim, the secondrim encompassing and projecting laterally outwardly from the second bodyportion, the second rim having a second plurality of ribs projectinggenerally downwardly therefrom such that second spaces are formedbetween adjacent ribs, the second rim having a generally concave shape,the second container being shaped substantially the same as the firstcontainer, wherein the first rim and the second rim have shapes thatcorrespond with each other when being releasably lockable to each other,wherein the first container and the second container are adapted to bereleasably lockable to each other by fitting the first plurality ofupwardly-projecting ribs into respective second spaces and fitting thesecond plurality of downwardly-projecting ribs into respective firstspaces.
 2. The container assembly of claim 1 wherein the first andsecond containers are bowls.
 3. The container assembly of claim 1wherein the first and second containers are plates.
 4. The containerassembly of claim 1 wherein the first container is a bowl and the secondcontainer is a plate.
 5. The container assembly of claim 1 wherein thefirst and second containers are platters.
 6. The container assembly ofclaim 1 wherein the first and second containers are made of polymericmaterial.
 7. The container assembly of claim 6 wherein the first andsecond containers are made of a mineral-filled polymeric material. 8.The container assembly of claim 6 wherein the first and secondcontainers include a high-impact polystyrene.
 9. The container assemblyof claim 1 wherein at least one of the first and second containers ispaper or metal.
 10. The container assembly of claim 1 wherein the firstplurality of upwardly-projecting ribs and the second plurality ofdownwardly-projecting ribs are generally perpendicular to the plane ofthe remainder of the respective rims.
 11. The container assembly ofclaim 10 wherein the first plurality of upwardly-projecting ribs and thesecond plurality of downwardly-projecting ribs are perpendicular to theplane of the remainder of the respective rims.
 12. The containerassembly of claim 1 wherein the first plurality of upwardly-projectingribs comprises first and second sidewalls spaced apart that are eachgenerally perpendicular to the plane of the remainder of the first rimand a generally first flat surface that encompasses and bridges thefirst and second sidewalls, and wherein the second plurality ofdownwardly-projecting ribs comprises third and fourth sidewalls spacedpart that are each generally perpendicular to the plane of the remainderof the second rim and generally second flat surface that encompasses andbridges the third and fourth sidewalls.
 13. The container assembly ofclaim 1 wherein the first plurality of upwardly-projecting ribscomprises first and second sidewalls and a surface that encompasses andbridges the first and second sidewalls, at least one of the first andsecond sidewalls has a first undercut, and wherein the second pluralityof downwardly-projecting ribs comprises third and fourth sidewalls and asurface that encompasses and bridges the third and fourth sidewalls, atleast one of the third and fourth sidewalls has a second undercut. 14.The container assembly of claim 1 wherein the first plurality ofupwardly-projecting ribs creates a first pattern that is generallynormal to the direction of the first rim, and the second plurality ofdownwardly-projecting ribs creates a second pattern that is generallynormal to the direction of the second rim.
 15. The container assembly ofclaim 14 wherein the first plurality of upwardly-projecting ribs createsa first pattern that is normal to the direction of the first rim, andthe second plurality of downwardly-projecting ribs creates a secondpattern that is normal to the direction of the second rim.
 16. Thecontainer assembly of claim 1 wherein each of the first plurality ofupwardly-projecting ribs is generally concentric with the center of thefirst container and each of the second plurality ofdownwardly-projecting ribs is generally concentric with the center ofthe second container.
 17. The container assembly of claim 1 wherein eachof the first plurality of upwardly-projecting ribs and the secondplurality of downwardly-projecting ribs includes at least about 20 ribs.18. The container assembly of claim 17 wherein each of the firstplurality of upwardly-projecting ribs and the second plurality ofdownwardly-projecting ribs includes at least about 40 ribs.
 19. Thecontainer assembly of claim 1 wherein the first rim and the second rimare adapted to form a seal.
 20. The container assembly of claim 19wherein the seal is located outwardly from the first plurality ofupwardly-projecting ribs and the second plurality ofdownwardly-projecting ribs.
 21. The container assembly of claim 19wherein the seal is located inwardly from the first plurality ofupwardly-projecting ribs and the second plurality ofdownwardly-projecting ribs.
 22. The container assembly of claim 1wherein each of the first plurality of upwardly-projecting ribs and thesecond plurality of downwardly-projecting ribs includes at least about 2sets of ribs.
 23. The container assembly of claim 1 wherein the firstand second containers are thermoformed.
 24. A method of forming acontainer assembly, the method comprising the acts of: providing a firstcontainer that includes a first continuous body portion and a first rim,the first rim encompassing and projecting laterally outwardly from thefirst body portion, the first rim having a first plurality of ribsprojecting generally upwardly therefrom such that first spaces areformed between adjacent ribs, the first rim having a generally convexshape; providing a second container that includes a second continuousbody portion and a second rim, the second rim encompassing andprojecting laterally outwardly from the second body portion, the rimhaving a second plurality of ribs projecting generally downwardlytherefrom such that second spaces are formed between adjacent ribs, thesecond rim having a generally concave shape, the second container beingshaped substantially the same as the first container; flipping one ofthe first container and the second container such that the firstcontainer and second container are generally aligned, the first andsecond rims are next to each other, and the first and second rimscorrespond with each other such that the first and second rims areeither both in a generally concave orientation or a generally convexorientation; and fitting the first plurality of upwardly-projecting ribsinto respective second spaces and fitting the second plurality ofdownwardly-projecting ribs into respective first spaces such that thefirst container and the second container are releasably lockable to eachother.
 25. The method of claim 24 further including placing a foodarticle on at least one of the first container and the second containerbefore fitting the first plurality of upwardly-projecting ribs intorespective second spaces and fitting the second plurality ofdownwardly-projecting ribs into respective first spaces.
 26. The methodof claim 24 wherein the first and second containers are bowls.
 27. Themethod of claim 24 wherein the first and second containers are plates.28. The method of claim 24 wherein the first and second containers aremade of polymeric material.
 29. The method of claim 28 wherein the firstand second containers include a high-impact polystyrene.
 30. The methodof claim 24 wherein the first plurality of upwardly-projecting ribs andthe second plurality of downwardly-projecting ribs are generallyperpendicular to the plane of the remainder of the respective rims. 31.The method of claim 24 wherein the first plurality ofupwardly-projecting ribs comprises first and second sidewalls and asurface that encompasses and bridges the first and second sidewalls, atleast one of the first and second sidewalls has a first undercut, andwherein the second plurality of downwardly-projecting ribs comprisesthird and fourth sidewalls and a surface that encompasses and bridgesthe third and fourth sidewalls, at least one of the third and fourthsidewalls has a second undercut.
 32. The method of claim 24 wherein thefirst plurality of upwardly-projecting ribs creates a first pattern thatis generally normal to the direction of the first rim, and the secondplurality of downwardly-projecting ribs creates a second pattern that isgenerally normal to the direction of the second rim.
 33. The method ofclaim 24 wherein each of the first plurality of upwardly-projecting ribsis generally concentric with the center of the first container and eachof the second plurality of downwardly-projecting ribs is generallyconcentric with the center of the second container.
 34. The method ofclaim 24 wherein the first rim and the second rim are adapted to form aseal.
 35. The method of claim 34 wherein the seal is located outwardlyfrom the first plurality of upwardly-projecting ribs and the secondplurality of downwardly-projecting ribs.
 36. A container assemblycomprising: a first container including a first continuous body portionand a first rim, the first rim encompassing and projecting laterallyoutwardly from the first body portion, the first rim having a firstplurality of upwardly projecting features with first spaces being formedbetween adjacent upwardly projecting features, the first rim having agenerally convex shape; and a second container including a secondcontinuous body portion and a second rim, the second rim encompassingand projecting laterally outwardly from the second body portion, the rimhaving a second plurality of downwardly projecting features with secondspaces being formed between adjacent downwardly projecting features, thesecond rim having a generally concave shape, the second container beingshaped substantially the same as the first container, wherein the firstcontainer and the second container are adapted to be releasably lockableto each other by fitting the first plurality of upwardly projectingfeatures into respective second spaces and fitting the second pluralityof downwardly projecting features into respective first spaces.
 37. Thecontainer assembly of claim 36 wherein the first and second containersare made of polymeric material.
 38. The container assembly of claim 36wherein the first rim and the second rim are adapted to form a seal. 39.The container assembly of claim 38 wherein the seal is located outwardlyfrom the first plurality of upwardly-projecting ribs and the secondplurality of upwardly-projecting ribs.
 40. The container assembly ofclaim 38 wherein the seal is located inwardly from the first pluralityof upwardly-projecting ribs and the second plurality ofupwardly-projecting ribs.
 41. A container assembly comprising: a firstcontainer including a first continuous body portion and a first rim, thefirst rim encompassing and projecting laterally outwardly from the firstbody portion, the first rim having a generally convex shape, the firstrim having a first plurality of ribs projecting generally upwardlytherefrom such that first spaces are formed between adjacent ribs, thefirst plurality of upwardly-projecting ribs creating a first patternthat is generally normal to the direction of the first rim, the firstplurality of upwardly-projecting ribs having at least one undercut; anda second container including a second continuous body portion and asecond rim, the second rim encompassing and projecting laterallyoutwardly from the second body portion, the second rim having agenerally concave shape, the second rim having a second plurality ofribs projecting generally downwardly therefrom such that second spacesare formed between adjacent ribs, the second plurality ofdownwardly-projecting ribs creating a second pattern that is generallynormal to the direction of the second rim, the second plurality ofdownwardly-projecting ribs having at least one undercut, the secondcontainer being shaped substantially the same as the first container,wherein the first container and the second container are adapted to bereleasably lockable to each other by fitting the first plurality ofupwardly-projecting ribs into respective second spaces and fitting thesecond plurality of downwardly-projecting ribs into respective firstspaces.
 42. The container assembly of claim 41 wherein the first andsecond containers are bowls.
 43. The container assembly of claim 41wherein the first and second containers are plates.
 44. The containerassembly of claim 41 wherein the first and second containers are made ofpolymeric material.
 45. The container assembly of claim 44 wherein thefirst and second containers include a high-impact polystyrene.
 46. Thecontainer assembly of claim 41 wherein the first plurality ofupwardly-projecting ribs creates a first pattern that is normal to thedirection of the first rim, and the second plurality ofdownwardly-projecting ribs creates a second pattern that is normal tothe direction of the second rim.
 47. The container assembly of claim 41wherein the first rim and the second rim are adapted to form a seal. 48.The container assembly of claim 41 wherein each of the first pluralityof downwardly-projecting ribs includes two undercuts and each of thesecond plurality of upwardly-projecting ribs includes two undercuts. 49.A container assembly comprising: a first container including a firstcontinuous body portion and a first rim, the first rim encompassing andprojecting laterally outwardly from the first body portion, the firstrim having a first plurality of ribs projecting generally upwardlytherefrom such that first spaces are formed between adjacent ribs, thefirst rim having a generally convex shape; and a second containerincluding a second continuous body portion and a second rim, the secondrim encompassing and projecting laterally outwardly from the second bodyportion, the second rim having a second plurality of ribs projectinggenerally downwardly therefrom such that second spaces are formedbetween adjacent ribs, the second rim having a generally concave shape,wherein the first rim and the second rim have shapes that correspondwith each other when being releasably lockable to each other, whereinthe first container and the second container are adapted to bereleasably lockable to each other by fitting the first plurality ofupwardly-projecting ribs into respective second spaces and fitting thesecond plurality of downwardly-projecting ribs into respective firstspaces.
 50. The container assembly of claim 49 wherein the first andsecond containers are made of polymeric material.
 51. The containerassembly of claim 50 wherein the first and second containers are made ofa mineral-filled polymeric material.
 52. The container assembly of claim50 wherein the first and second containers include a high-impactpolystyrene.
 53. The container assembly of claim 49 wherein the firstplurality of upwardly-projecting ribs and the second plurality ofdownwardly-projecting ribs are generally perpendicular to the plane ofthe remainder of the respective rims.
 54. The container assembly ofclaim 49 wherein the first plurality of upwardly-projecting ribscomprises first and second sidewalls and a surface that encompasses andbridges the first and second sidewalls, at least one of the first andsecond sidewalls has a first undercut, and wherein the second pluralityof downwardly-projecting ribs comprises third and fourth sidewalls and asurface that encompasses and bridges the third and fourth sidewalls, atleast one of the third and fourth sidewalls has a second undercut. 55.The container assembly of claim 49 wherein the first plurality ofupwardly-projecting ribs creates a first pattern that is generallynormal to the direction of the first rim, and the second plurality ofdownwardly-projecting ribs creates a second pattern that is generallynormal to the direction of the second rim.
 56. The container assembly ofclaim 55 wherein the first plurality of upwardly-projecting ribs createsa first pattern that is normal to the direction of the first rim, andthe second plurality of downwardly-projecting ribs creates a secondpattern that is normal to the direction of the second rim.
 57. Thecontainer assembly of claim 49 wherein each of the first plurality ofupwardly-projecting ribs and the second plurality ofdownwardly-projecting ribs includes at least about 20 ribs.
 58. Thecontainer assembly of claim 57 wherein each of the first plurality ofupwardly-projecting ribs and the second plurality ofdownwardly-projecting ribs includes at least about 40 ribs.
 59. A methodof forming a container assembly, the method comprising the acts of:providing a first container that includes a first continuous bodyportion and a first rim, the first rim encompassing and projectinglaterally outwardly from the first body portion, the first rim having afirst plurality of ribs projecting generally upwardly therefrom suchthat first spaces are formed between adjacent ribs, the first rim havinga generally convex shape; providing a second container that includes asecond continuous body portion and a second rim, the second rimencompassing and projecting laterally outwardly from the second bodyportion, the rim having a second plurality of ribs projecting generallydownwardly therefrom such that second spaces are formed between adjacentribs, the second rim having a generally concave shape; flipping one ofthe first container and the second container such that the firstcontainer and second container are generally aligned, the first andsecond rims are next to each other, and the first and second rimscorrespond with each other such that the first and second rims areeither both in a generally concave orientation or a generally convexorientation; and fitting the first plurality of upwardly-projecting ribsinto respective second spaces and fitting the second plurality ofdownwardly-projecting ribs into respective first spaces such that thefirst container and the second container are releasably lockable to eachother.
 60. The method of claim 59 further including placing a foodarticle on at least one of the first container and the second containerbefore fitting the first plurality of upwardly-projecting ribs intorespective second spaces and fitting the second plurality ofdownwardly-projecting ribs into respective first spaces.
 61. The methodof claim 59 wherein the first and second containers are made ofpolymeric material.
 62. The method of claim 59 wherein the firstplurality of upwardly-projecting ribs comprises first and secondsidewalls and a surface that encompasses and bridges the first andsecond sidewalls, at least one of the first and second sidewalls has afirst undercut, and wherein the second plurality ofdownwardly-projecting ribs comprises third and fourth sidewalls and asurface that encompasses and bridges the third and fourth sidewalls, atleast one of the third and fourth sidewalls has a second undercut. 63.The method of claim 59 wherein the first plurality ofupwardly-projecting ribs creates a first pattern that is generallynormal to the direction of the first rim, and the second plurality ofdownwardly-projecting ribs creates a second pattern that is generallynormal to the direction of the second rim.
 64. The method of claim 59wherein the first rim and the second rim are adapted to form a seal. 65.A container assembly comprising: a first container including a firstcontinuous body portion and a first rim, the first rim encompassing andprojecting laterally outwardly from the first body portion, the firstrim having a first plurality of upwardly projecting features with firstspaces being formed between adjacent upwardly projecting features, thefirst rim having a generally convex shape; and a second containerincluding a second continuous body portion and a second rim, the secondrim encompassing and projecting laterally outwardly from the second bodyportion, the rim having a second plurality of downwardly projectingfeatures with second spaces being formed between adjacent downwardlyprojecting features, the second rim having a generally concave shape,wherein the first container and the second container are adapted to bereleasably lockable to each other by fitting the first plurality ofupwardly projecting features into respective second spaces and fittingthe second plurality of downwardly projecting features into respectivefirst spaces.
 66. The container assembly of claim 65 wherein the firstand second containers are made of polymeric material.
 67. The containerassembly of claim 65 wherein the first rim and the second rim areadapted to form a seal.
 68. The container assembly of claim 67 whereinthe seal is located outwardly from the first plurality ofupwardly-projecting ribs and the second plurality of upwardly-projectingribs.
 69. The container assembly of claim 67 wherein the seal is locatedinwardly from the first plurality of upwardly-projecting ribs and thesecond plurality of upwardly-projecting ribs.
 70. A container assemblycomprising: a first container including a first continuous body portionand a first rim, the first rim encompassing and projecting laterallyoutwardly from the first body portion, the first rim having a generallyconvex shape, the first rim having a first plurality of ribs projectinggenerally upwardly therefrom such that first spaces are formed betweenadjacent ribs, the first plurality of upwardly-projecting ribs creatinga first pattern that is generally normal to the direction of the firstrim, the first plurality of upwardly-projecting ribs having at least oneundercut; and a second container including a second continuous bodyportion and a second rim, the second rim encompassing and projectinglaterally outwardly from the second body portion, the second rim havinga generally concave shape, the second rim having a second plurality ofribs projecting generally downwardly therefrom such that second spacesare formed between adjacent ribs, the second plurality ofdownwardly-projecting ribs creating a second pattern that is generallynormal to the direction of the second rim, the second plurality ofupwardly-projecting ribs having at least one undercut, the firstcontainer being shaped substantially the same as the second container,wherein the first container and the second container are adapted to bereleasably lockable to each other by fitting the first plurality ofupwardly-projecting ribs into respective second spaces and fitting thesecond plurality of downwardly-projecting ribs into respective firstspaces.
 71. The container assembly of claim 70 wherein the first andsecond containers are made of polymeric material.
 72. The containerassembly of claim 70 wherein the first plurality of upwardly-projectingribs creates a first pattern that is normal to the direction of thefirst rim, and the second plurality of downwardly-projecting ribscreates a second pattern that is normal to the direction of the secondrim.
 73. The container assembly of claim 70 wherein the first rim andthe second rim are adapted to form a seal.